Full text loading...
(a) A schematic of the MOEIC. A magnetic field changes the resistance of the spin valve. The MR is amplified by the cascaded transconductance HEMT amplifier to a large change in drain-to-source current which modulates the light intensity of the LED. The resistors and are used to correctly bias the cascaded HEMT amplifier in the linear region; (b) a schematic of the MOEIC heterostructure grown by MBE. The heterostructure consists of epitaxially grown layers for the MnAs/GaAs lateral spin valve, the multi-quantum-well LED and the pseudomorphic HEMT separated by undoped GaAs buffer layers.
A schematic and a microphotograph of the fabricated MOEIC (before the final interconnection and metallization step). The Ti resistors and are delineated on undoped GaAs buffer layers by physical vapor deposition and lift-off technique.
Characteristics of the individual circuit elements. (a) The spin valve shows two MR peaks corresponding to the case when the polarizer and the analyzer are magnetized in opposite directions. The MR decreases with increasing temperature due to decreasing spin-relaxation time; (b) spin precession measurement in a perpendicular magnetic field. The small asymmetry is due to sample misalignment (Ref. 17); (c) transconductance of the HEMT as a function of gate-to-source voltage. It reaches peak at ; (d) transconductance of the HEMT as a function temperature. It increases with decreasing temperature due to increasing mobility; (e) LED light output and terminal voltage as a function of bias current; (f) light output vs bias current of the LED as a function of temperature. The quantum efficiency increases with decreasing temperature, hence, the slope increases.
MOEIC characteristics. Modulation of LED light intensity as a function of magnetic field. The light intensity modulation shows exactly the same magnetic field dependence as the spin-valve characteristics. The MR amplification is determined to be in the region of operation. The MOEIC acts as a magnetoelectronic switch which varies LED light intensity in response to an external magnetic field.
Article metrics loading...